The biggest difference re: potential that I see is capacity. A given ski slope, even a small one, can accommodate hundreds of skiers over the course of a day. A large slope on a big mountain can handle thousands, and ski mountains may have dozens of different runs. How many water skiers can a single dedicated ski lake handle daily? Let's assume a meaningful day of slalom skiing might be, say, 3 sets, 6-8 passes per set. So maybe each set is around 15 minutes per skier. Just a single skier might then monopolize the lake for around 45 minutes over the course of the day. There are only so many hours in a day, and even if the boat ran continuously, never stopping for fuel, to change drivers, for lunch... for anything... a ski lake can only handle a very few skiers per day. If there were 12 hours of daylight, this lake could offer just 16 skiers quality ski time. Obviously I've pulled some numbers out of the air to illustrate the problem as I see it. You can double that number of skiers and the fact remains an entire ski lake has very very low skier capacity and the number of dedicated ski lakes is certainly limited. Public lakes might be bigger, but they suffer from rollers generated by other boat traffic, so the number of skiers who can enjoy a quality slalom ski experience on a public lake is also extremely limited. Just waiting for a roller-free window for a single pass can take a while. I just don't see how this sport can accommodate large numbers of participants even if the interest was there.